智能革命何以驱动乡村振兴:价值共建、能态激发与社会再组织

智能革命浪潮正在深刻影响着乡村振兴的战略发展进程。乡村振兴的根本目的在于建构形成符合社会主义核心价值观的均衡发展格局,其要旨在于消除城乡间发展“不均衡、不充分”的阶段性矛盾。新一轮智能革命正从更具建设性的角度出发,通过乡村价值的赋魅共建、乡村能态的拓展激活与乡村社会的再组织,驱动着乡村在新时期、新格局下实现振兴。

Energies and Transition Rates of Low-Lying Excited States for Beryllium

Low lying excited states of beryllium are calculated with multiconfiguration interaction method. The relativisitic corrections and mass polarization are included. The oscillator strength and radiation rates are also calculated. Our results are in good agreement with other theoretical data.

Theoretical Investigation on Triplet Excitation Energy Transfer in Fluorene Dimer

Triplet-triplet energy transfer in fluorene dimer with electronic structure calculations. The two is investigated by combining rate theories key parameters for the control of energy transfer, electronic coupling and reorganization energy, are calculated based on the diabatic states constructed by the constrained density functional theory. The fluctuation of the electronic coupling is further revealed by molecular dynamics simulation. Succeedingly, the diagonal and off-diagonal fluctuations of the Hamiltonian are mapped from the correlation functions of those parameters, and the rate is then estimated both from the perturbation theory and wavepacket diffusion method. The results manifest that both the static and dynamic fluctuations enhance the rate significantly, but the rate from the dynamic fluctuation is smaller than that from the static fluctuation.

Adiabatic Potential Energy Surfaces and Photodissociation Mechanisms for Highly Excited States of H_(2)O

Full-dimensional adiabatic potential energy surfaces of the electronic ground state X and nine excited states A,I,B,C,D,D',D'',E' and F of H_(2)O molecule are developed at the level of internally contracted multireference configuration interaction with the Davidson correction.The potential energy surfaces are fitted by using Gaussian process regression combining permutation invariant polynomials.With a large selected active space and extra diffuse basis set to describe these Rydberg states,the calculated vertical excited energies and equilibrium geometries are in good agreement with the previous theoretical and experimental values.Compared with the well-investigated photodissociation of the first three low-lying states,both theoretical and experimental studies on higher states are still limited.In this work,we focus on all the three channels of the highly excited state,which are directly involved in the vacuum ultraviolet photodissociation of water.In particular,some conical intersections of D-E',E'-F,A-I and I-C states are clearly illustrated for the first time based on the newly developed potential energy surfaces(PESs).The nonadiabatic dissociation pathways for these excited states are discussed in detail,which may shed light on the photodissociation mechanisms for these highly excited states.

Upconversion Luminescence of SrTiO3：Er^3＋ Ultrafine Powders Produced by 785 nm Laser

Er^3＋ doped SrTiO3 ultrafine powders were prepared by solid state reaction in a molten NaCl flux. The structural properties were characterized by X-ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. The Stokes emission spectra of Er^3＋ in SrTiO3：Er^3＋ ranging from green to near infrared region were investigated under 514.5 nm laser excitation. The green and red upconverted luminescence spectra of Er^3＋ were measured under excitation into the 419/2 level by 785 nm laser. The upconversion mechanisms were studied in detail through laser power dependence and Er^3＋ ion concentration dependence of upconverted emissions, and results show that excited state absorption and energy transfer process are the possible mechanisms for the upconversion. The upconversion properties indicate that SrTiO3：Er^3＋ may be used in upconversion phosphors.

Long-lived Single Excitons, Trions, and Biexcitons in CdSe/CdTe Type-II Colloidal Quantum Wells

Light-harvesters with long-lived excited states are desired for efficient solar energy conversion systems. Many solar-to-fuel conversion reactions, such as H2 evolution and CO2 reduction, require multiple sequential electron transfer processes, which leads to a complicated situation that excited states involves not only excitons （electron-hole pairs） but also multi-excitons and charged excitons. While long-lived excitons can be obtained in various systems （e.g., semiconductor nanocrystals）, multi-excitons and charged excitons are typically shorted-lived due to nonradiative Auger recombination pathways whereby the recombination energy of an exciton is quickly transferred to the third carrier on a few to hundreds of picoseconds timescale. In this work, we report a study of excitons, trions （an exciton plus an additional charge）, and biexcitons in CdSe/CdTe colloidal quantum wells or nanoplatelets. The type- II band alignment effectively separates electrons and holes in space, leading to a single exciton lifetime of 340 ns which is -2 order of magnitudes longer than that in plane CdSe nanoplatelets. More importantly, the electron-hole separation also dramatically slows down Auger decay, giving rise to a trion lifetime of 70 ns and a biexciton lifetime of 11 ns, among the longest values ever reported for colloidal nanocrystals. The long-lived exciton, trion, and biexciton states, combined with the intrinsically strong light-absorption capability of two-dimensional systems, enable the CdSe/CdTe type-II nanoplatelets as promising light harvesters for efficient solar-to-fuel conversion reactions.

Two-Photon Dissociation Dynamics of Hydroxyl Radical

Two-photon dissociation dynamics of the OH radical is studied using the high-n Rydberg atom time-of-flight(HRTOF) technique. The H(2 S)+O(1 D) and H(2 S)+O(1 S) product channels are observed in the dissociation of the OH radical on the 22Π and B2Σ+repulsive states, respectively, from sequential two-photon excitation via the A2Σ+(v′=2, J′=0.5-2.5)state. Both H+O product channels have anisotropic angular distributions, with β=-0.97 for H(2 S)+O(1 D) and 1.97 for H(2 S)+O(1 S). The anisotropic angular distributions are consistent with a mechanism of OH direct dissociation on the repulsive potential energy curves(PECs) leading to the H+O products. The OH bond dissociation energy D0(O-H) is determined to be 35580±15 cm-1.

High Accuracy Calculation for Excited-State Energies of H Atoms in a Magnetic Field

Using the recently developed finite-basis-set method with B splines, excited states of H atoms in a magnetic field have been calculated. Energy levels are presented for the ten excited states, 2so, 3d＇0, 3po, 3p-1, 3d_1, 4d-1, 3d-2, 4d-2, 4f-2 , and 5f-2 as a function of magnetic field strengths with a range from zero up to 2.35 × 10^6 T. The obtained results are compared with available high accuracy theoretical data reported in the literature and found to be in excellent agreement. The comparison also shows that the current method can produce energy levels with an accuracy higher than the existing high accuracy method [Phys. Rev. A 54 （1996） 287]. Here high accuracy energy levels are for the first time reported for the 3d＇0, 4d-1, 4d-2, 4f-2, and 5f-2 states.

Laser-induced Fluorescence Excitation Spectrum of NiS in 15500-17200 cm^-1

The laser-induced fluorescence excitation spectrum of jet-cooled NiS molecule has been recorded in the energy range of 15500 17200 cm-1. Fifteen bands have been assigned as three transition progressions：[15.65]^3Ⅱ1（v′=0-4）-X^3∑0^-（v″=0）,[15.69]^3∑0^-（v′=0-4）-X^3∑0^-（v″=0）,and [15.81]^3Ⅱ1（v′=0-4）-X^3∑0^-（v″=0）.Spectroscopic constants for the three newly identified electronically excited states have been determined for the first time. In addition,the lifetimes for most observed vibronic bands have also been measured.

Binding Energy of D^- and D^0 Centers Confined by Spherical Quantum Dots

We study a negative donor center, a neutral donor in a spherical Gaussian potential quantum dot by using the matrix diagonalization of Hamiltonian within the effective-mass approximation. We calculate the energy E（ D^-） as functions of Gaussian potential size and depth, the same calculations as performed with the parabolic approximation. The dependence of the ground state of the neutral shallow donor and the negatively charged donor on the dot size and the potential depth is investigated.

GW/BSE Nonadiabatic Dynamics Simulations on Excited-State Relaxation Processes of Zinc Phthalocyanine-Fullerene Dyads:Roles of Bridging Chemical Bonds

In this work,we employ electronic structure calculations and nonadiabatic dynamics simulations based on many-body Green function and BetheSalpeter equation(GW/BSE)methods to study excited-state properties of a zinc phthalocyanine-fullerene(ZnPcC_(60))dyad with 6-6 and 5-6 configurations.In the former,the initially populated locally excited(LE)state of ZnPc is the lowest S1 state and thus,its subsequent charge separation is relatively slow.In contrast,in the latter,the S1 state is the LE state of C_(60)while the LE state of ZnPc is much higher in energy.There also exist several charge-transfer(CT)states between the LE states of ZnPc and C_(60).Thus,one can see apparent charge separation dynamics during excited-state relaxation dynamics from the LE state of ZnPc to that of C_(60).These points are verified in dynamics simulations.In the first 200 fs,there is a rapid excitation energy transfer from ZnPc to C_(60),followed by an ultrafast charge separation to form a CT intermediate state.This process is mainly driven by hole transfer from C_(60)to ZnPc.The present work demonstrates that different bonding patterns(i.e.5-6 and 6-6)of the C−N linker can be used to tune excited-state properties and thereto optoelectronic properties of covalently bonded ZnPc-C_(60)dyads.Methodologically,it is proven that combined GW/BSE nonadiabatic dynamics method is a practical and reliable tool for exploring photoinduced dynamics of nonperiodic dyads,organometallic molecules,quantum dots,nanoclusters,etc.

Nonclassical Effects of a Four-Level Excited-Doublet Atom Model

We adopt a dynamical algebraic method to study a four-level excited-doublet atom model and obtain the explicit expressions of the time-evolution operator and the density operator for the system. The nonclassical effects of the system, such as collapses and revivals of the atomic inversion and squeezing of the radiation field, are also discussed.

共轭核(N=Z)低激发谱特征的微观相互作用玻色子模型研究

在唯象和微观玻色子相互作用模型（IBM）中,由于存在中子-质子自由度,它们对激发能的相对贡献率始终没有研究清楚.本研究提出：假定处在同一大壳层上中子数和质子数相等（N=Z）的共轭核中,它们对低激发态应该贡献出相等的激发能,这就绕开了对它们能量分摊评估的一大难题.本文采用28~50核子大壳层的实验能级值,对6个偶-偶核,64 Ge6832,Se34,72 Kr7636,Sr38,80Zr40和84 Mo42,的低激发能谱作了理论计算,计算能谱很好地再现了复杂的实验测量谱,支持上述推测.据此得到的能级值,中子-质子间等效相互作用强度参数等可以作为进一步研究的起点.

Effects of Mo on phase structure and up-conversion emissions of Er:Al_2O_3 nanocrystals

A simple and efficient approach was presented to enhance up-conversion emissions significantly for the Er：Al2O3 nanocrystals by Mo support （Er-Mo：Al2O3） with a 976 nm laser diode excitation. Mo support had evident effects on the phase structure and up-conversion emissions for the Er：Al2O3 nanocrystals, which promoted the θ-（Al,Er）2O3 transformed to α-（Al,Er,Mo）203 phase, Compared with the Er：Al2O3, the maximal green and red up-conversion emissions intensities increased about 3×10^3 and 1.4×10^2 times for the Er-Mo：Al2O3 nanocrystals, respectively. It suggests that the enhancement of up-conversion emissions is caused by the high excited state energy transfer process from [4115/2, 3T2） state of the Er3＋-MoO2- dimer to the 4F7/2 level of E3＋.

Development and prospect of high-power Yb^(3+) doped fibers

Ytterbium-doped fibers have become the optimum gain media of high-power fiber lasers thanks to a simple energy structure, which strongly reduces the excited state absorption, and a low quantum defect and a high optic–optic conversion efficiency, which means the low thermal load. In this paper, we take a review of the current state of the art in terms of Yb^(3+)doped fibers for high-power fiber lasers, including the development of the fabrication techniques. The research work to overcome the challenges for Yb3+doped fibers, which affect the stability of output power and beam quality, will be demonstrated. Direction of further research is presented and the goal is to look for a fiber design, to boost single fiber output power, stabilize the laser power and support robust single-mode operation.

Bonded excimer in stacked adenines:Semiclassical simulations

The nonradiative decay of a n-stacked pair of adenine molecules, one of which was excited by an ultrafast laser pulse, is studied by semiclassical dynamics simulations. This simulation investigation is focused on the effect of the formation of bonded excimer in stacked adenines on the mechanism of ultrafast decay. The simulation finds that the formation of the bond- ed excimer significantly lowers the energy gap between the LUMO and HOMO and consequently facilitates the deactivation of the electronically excited molecule. On the other hand, the formation of the chemical bond between two stacked adenines re- stricts the deformation vibration of the pyrimidine of the excited molecule due to the steric effect. This slows down the formation of the coupling between the HOMO and LUMO energy levels and therefore delays the deactivation process of the excited adenine molecule to the electronic ground state.

Exact Eigenfunctions of N-body System with Quadratic Pair Potential

We obtain the energy spectrum and all the corresponding eigenfunctions of N-body Bose and Fermi systems with Quadratic Pair Potentials in one dimension. The original first excited state or energy level is disappeared in one dimension, which results from the operation of symmetry or antisymmetry of identical particles. In two and higher dimensions, we give the energy spectrum and the analytical ground state wave [unctions and the degree of degeneracy. By comparison, we refine A vinash Khare＇s results by making some items in his article precisely.

Temperature Effects of Electric Field on the First Excited State of Strong Coupling Polaron in a CsI Quantum Pseudodot

Employing variational method of Pekar type(VMPT), this paper investigates the first-excited state energy(FESE), excitation energy and transition frequency of the strongly-coupled polaron in the Cs I quantum pseudodot(QPD)with electric field. The temperature effects on the strong-coupling polaron in electric field are calculated by using the quantum statistical theory(QST). The results from the present investigation show that the FESE, excitation energy and transition frequency increase(decrease) firstly and then at lower(higher) temperature regions. They are decreasing functions of the electric field strength.